Paper Feed Cassette and Image Forming Apparatus

ABSTRACT

A paper feed cassette provided with a size detection mechanism that detects the size of paper contained in the paper feed cassette, the size detection mechanism including: a link plate that moves along a paper feed direction with movement of side limitation plates in the width direction; a size detection member that is provided relative to the link plate, that moves with movement of the link plate along the paper feed direction, and that can enter a state in which the size detection member is abutting or not abutting an externally provided size detection sensor in the width direction of the paper; and a biasing member that provides the link plate with a biasing force in a direction of the movement of the link plate.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is based on Japanese Patent Application No. 2015-133665 filed with the Japan Patent Office on Jul. 2, 2015, the entire content of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to image forming apparatuses such as a copying machine, a printer and a facsimile, and relates to the configuration of a paper feed cassette, and an image forming apparatus including the paper feed cassette.

Description of the Related Art

An image forming apparatus is provided with a size detection mechanism that detects the size of paper contained in a paper feed cassette. Japanese Laid-Open Patent Publication Nos. 2002-187626 and 2008-81259 each disclose a paper feed cassette provided with such a size detection mechanism, and an image forming apparatus including the paper feed cassette.

SUMMARY OF THE INVENTION

A size detection mechanism provided in a paper feed cassette is required to operate with stability. If the size detection mechanism becomes unstable in operation and incapable of correct detection of the paper size, the reliability of operation of an image forming apparatus is affected.

The present invention has been made in view of the aforementioned problem, and an object of the invention is to provide a paper feed cassette capable of ensuring stability of operation of a size detection mechanism provided in the paper feed cassette, and an image forming apparatus including the paper feed cassette.

To achieve at least one of the abovementioned objects, a paper feed cassette reflecting one aspect of the present invention is a paper feed cassette provided with a size detection mechanism that detects the size of paper contained in the paper feed cassette, the size detection mechanism including: a pair of side limitation plates that abuts opposite lateral sides of the paper from a width direction intersecting a paper feed direction of the paper; a link member that moves along the paper feed direction with movement of the side limitation plates in the width direction; a size detection member that is provided relative to the link member, that moves with movement of the link member along the paper feed direction, and that can enter a state in which the size detection member is abutting or not abutting an externally provided size detection sensor in the width direction of the paper; and a biasing member that provides the link member with a biasing force in a direction of the movement of the link member.

In another aspect, a direction in which the link member is biased by the biasing member is a direction in which the limitation plates abut the paper in the width direction of the paper.

In another aspect, the link member biased by the biasing member causes the pair of side limitation plates to press the paper.

In another aspect, the size detection mechanism further includes a coupling rod that couples the link member to the size detection member.

In another aspect, the paper feed cassette includes a bottom surface forming the bottom of the paper feed cassette, in which the pair of side limitation plates is disposed on the inner surface side of the bottom surface, and the link member is disposed on the outer surface side of the bottom surface.

In another aspect, the link member has a rotation fulcrum at an inner position in the width direction, the size detection member is shaft-supported at the link member at an outer position in the width direction as seen from the rotation fulcrum, and the biasing member is biasing the link member in a direction that causes the link member to pivot around the rotation fulcrum.

To achieve at least one of the abovementioned objects, an image forming apparatus reflecting one aspect of the present invention includes an image forming unit; and a paper feed unit that stores a plurality of sheets of paper to be transported to the image forming unit, the paper feed unit including any one of the paper feed cassettes described above that accumulates and stores the paper.

The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the overall configuration of an image forming apparatus according to an embodiment.

FIG. 2 is a vertical cross-sectional view showing the overall configuration (excluding a scanner unit) of the image forming apparatus according to the embodiment.

FIG. 3 is a perspective view from the top side showing the overall configuration of a paper feed cassette used in the image forming apparatus according to the embodiment.

FIG. 4 is a perspective view from the bottom side showing the overall configuration of the paper feed cassette used in the image forming apparatus according to the embodiment.

FIG. 5 is a diagram illustrating a size detection mechanism including side limitation plates, a link plate, and a lateral direction width size detection member according to the embodiment.

FIG. 6 is a diagram showing the configuration of the link plate as seen from the bottom side.

FIG. 7 is a vertical cross-sectional view showing engagement relation between the lateral direction width size detection member and the link plate as seen along an arrowed line VII in FIG. 5.

FIG. 8 is a front perspective view showing a link mechanism of the size detection mechanism according to another embodiment.

FIG. 9 is a rear perspective view showing the link mechanism of the size detection mechanism according to another embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A paper feed cassette and an image forming apparatus in an embodiment based on the present invention will now be described with reference to the drawings. When a number, an amount or the like is mentioned in the embodiment described below, the scope of the present invention is not necessarily limited to the number, the amount or the like unless otherwise specified. The same or corresponding components are designated by the same reference numbers and redundant description may not be repeated. In addition, it is originally intended to appropriately combine and use configurations in each embodiment.

General Configuration of Image Forming Apparatus 1

Referring to FIGS. 1 and 2, the general configuration of an image forming apparatus 1 in this embodiment is described. FIG. 1 is a perspective view showing the overall configuration of image forming apparatus 1, and FIG. 2 is a vertical cross-sectional view showing the overall configuration (excluding a scanner unit) of image forming apparatus 1.

This image forming apparatus 1 is a copying machine, a printer, a facsimile, an MFP or the like, in which electrophotography is employed as a process of forming an image on paper. In electrophotography, a visible toner image is formed on a photoreceptor and transferred onto a sheet of paper such as plain paper. In order to retain this toner image on the sheet of paper as a permanent image on the sheet, the sheet is passed through a heat-fusing device, for example, to fuse the toner thereon, and then the sheet is ejected outside image forming apparatus 1.

Image forming apparatus 1 includes a body housing 1A. An operation panel unit 2 and a scanner unit 3 are provided in the upper portion of body housing 1A. Body housing 1A includes therein an image forming unit 10, and a paper feed unit 20, below image forming unit 10, that stores a plurality of sheets of paper to be transported to image forming unit 10. Paper feed unit 20 includes a plurality of paper feed cassettes 100 and 150 that accumulate and store sheets of paper of the same size or sheets of paper of different sizes. The numbers of paper feed cassettes 100 and 150 can be changed depending on the performance required of image forming apparatus 1. Body housing 1A has a manual paper feed unit 4 provided on its side.

Paper Feed Cassette 100

Referring to FIGS. 3 and 4, the configuration of paper feed cassette 100 is described. FIG. 3 is a perspective view from the top side showing the overall configuration of paper feed cassette 100 used in image forming apparatus 1, and FIG. 4 is a perspective view from the bottom side showing the overall configuration of paper feed cassette 100 used in image forming apparatus 1. Paper feed cassette 150 with a paper capacity higher than that of paper feed cassette 100 has the same basic configuration as that of paper feed cassette 100, and thus the description thereof will be omitted here.

Paper feed cassette 100 is provided such that it can be pulled out or pushed in along the direction of an arrow CD in the figure (pullout direction CD) relative to image forming apparatus 1. Relative to pullout direction CD of paper feed cassette 100, a transport direction of the paper in image forming apparatus 1 is the direction of an arrow FD in the figure (transport direction FD).

Paper feed cassette 100 includes, so as to define a hollow paper containing section, a front wall 110 b located at the front in pullout direction CD relative to bottom surface 110 a, and a back wall 110 c located at the back in pullout direction CD. In addition, a side wall 110 d and a side wall 110 e are provided in transport direction FD as well.

On the inner surface side of paper feed cassette 100, there is provided a pair of side limitation plates 101 a and 101 a, the detailed structure of which will be described later, which is provided such that it can move in pullout direction CD relative to bottom surface 110 a, and which abuts opposite lateral sides of the paper from a direction intersecting the paper feed direction (transport direction FD).

In addition, on the inner surface side of paper feed cassette 100, there is provided a back end limitation plate 203, which is provided such that it can move relative to bottom surface 110 a, and which abuts a rear side of the paper from the back in the paper feed direction (transport direction FD).

In addition, back wall 110 c is provided with a transport direction width size detection member 201. Transport direction width size detection member 201 is provided such that it can slide along a wall surface of back wall 110 c, and includes a region which abuts and/or does not about a transport direction width size detection push switch 350 provided on body housing 1A when paper feed cassette 100 is mounted on body housing 1A.

Likewise, back wall 110 c is provided with a lateral direction width size detection member 310 (detection actuator) 310. Lateral direction width size detection member 310 (detection actuator) 310 is provided such that it can slide along the wall surface of back wall 110 c, and includes a region which abuts and/or does not about a lateral direction width size detection push switch 360 provided on body housing 1A when paper feed cassette 100 is mounted on body housing 1A.

On the outer surface side of bottom surface 110 a, a link bar 202 is disposed. Link bar 202 has one end coupled to back end limitation plate 203 via an engagement shaft P2 and the other end coupled to transport direction width size detection member 201 via an engagement shaft P3, and causes sliding movement of transport direction width size detection member 201 along the wall surface of back wall 110, with the movement of back end limitation plate 203.

On the outer surface side of bottom surface 110 a, a link plate 320 serving as a link member is disposed. Link plate 320 is disposed on the outer surface side of bottom surface 110 a at an inner position in the width direction, with a rotation fulcrum R1 as the center of rotation. Link plate 320 is shaft-supported to one of side limitation plates 101 a via an engagement shaft P5 at an outer position in the width direction as seen from rotation fulcrum R1, and additionally is coupled to lateral direction width size detection member 310 via an engagement shaft P4. Link plate 320 causes sliding movement of lateral direction width size detection member 310 along the wall surface of back wall 110 c, with the movement of the one of side limitation plates 101 a.

In addition, on the outer surface side of bottom surface 110 a, a coil spring 400 serving as a biasing member is provided between link plate 320 and bottom surface 110 a. Coil spring 400 has one end 401 fixed to an engagement unit 110 x provided on bottom surface 110 a (see FIG. 6), and coil spring 400 has the other end 402 fixed in an engagement hole 320 h provided in link plate 320 (see FIG. 6). In a normal state, by the biasing force of coil spring 400, force is exerted on link plate 320 such that link plate 320 is always pulled in the direction of an arrow F, a substantially horizontal direction, with rotation fulcrum R1 as the center of rotation.

Size Detection Mechanism

Referring now to FIGS. 5 to 7, the operation of side limitation plates 101 a, link plate 320, and lateral direction width size detection member 310 is described. A size detection mechanism is formed of at least side limitation plates 101 a, link plate 320, and lateral direction width size detection member 310.

FIG. 5 is a diagram illustrating the size detection mechanism including side limitation plates 101 a, link plate 320, and lateral direction width size detection member 310, FIG. 6 is a diagram showing the configuration of link plate 320 as seen from the bottom side, and FIG. 7 is a vertical cross-sectional view showing engagement relation between lateral direction width size detection member 310 and link plate 320 as seen along an arrowed line VII in FIG. 5.

Referring to FIG. 5, each of the pair of side limitation plates 101 a disposed opposite to each other is provided with a rack 101 b. Each rack 101 b is screwed to a pivotable pinion 101 d. Moving one of side limitation plates 101 a so as to adapt to the size of placed paper causes simultaneous movement of the other side limitation plate 101 a.

Engagement shaft P5 provided at a lower end of one of side limitation plates 101 a fits in a guide groove G1 provided in link plate 320. As this side limitation plate 101 a moves, engagement shaft P5 moves within guide groove G1. Guide groove G1 has a groove shape for causing link plate 320 to pivot with rotation fulcrum R1 as the center of rotation depending on the paper size.

Guide groove G1 is formed such that, owing to the engagement relation between engagement shaft P5 and guide groove G1, the direction in which link plate 320 is biased by coil spring 400 (direction of arrow F) is a direction in which side limitation plates 101 a abut the paper in the width direction of paper. In this embodiment, link plate 320 biased by coil spring 400 causes the pair of side limitation plates 101 a and 101 a to press the paper.

Engagement shaft P4 is provided at a lower end of lateral direction width size detection member 310 as well, and fits in a guide groove G4 provided in link plate 320. Pivoting of side limitation plate 101 a with rotation fulcrum R1 as the center of rotation as described above causes sliding movement of lateral direction width size detection member 310 along the wall surface of back wall 110 c.

Referring now to FIGS. 6 and 7, the function and effect of coil spring 400 serving as a biasing member is described. In this embodiment, as described above, coil spring 400 serving as a biasing member is provided between link plate 320 and bottom surface 110 a. Coil spring 400 has one end 401 fixed to engagement unit 110 x provided on bottom surface 110 a, and coil spring 400 has the other end 402 fixed in engagement hole 320 h provided in link plate 320.

In a normal state, by the biasing force of coil spring 400, force is exerted on link plate 320 such that link plate 320 is always pulled in the direction of arrow F, with rotation fulcrum R1 as the center of rotation. As a result, as shown in FIG. 7, engagement shaft P4 of lateral direction width size detection member 310 is always pressed against one side of guide groove G4 in link plate 320. This relation also applies between engagement shaft P5 provided at the lower end of one of side limitation plates 101 a and guide groove G1.

Thus, when coil spring 400 is not provided, there has conventionally been a gap formed between engagement shaft P4 and guide groove G4, sometimes resulting in clattering of lateral direction width size detection member 310 as well as a tilt of lateral direction width size detection member 310 during movement of lateral direction width size detection member 310. Consequently, lateral direction width size detection member 310 has sometimes been placed in a position different from a position of the original paper size, resulting in detection of the wrong paper size.

In this embodiment, by contrast, engagement shaft P4 of lateral direction width size detection member 310 is always pressed against one side of guide groove G4 in link plate 320 owing to the provision of coil spring 400, so that the occurrence of clattering of lateral direction width size detection member 310 can be suppressed during movement of lateral direction width size detection member 310. As a result, a tilt of lateral direction width size detection member 310 can be suppressed, thus allowing lateral direction width size detection member 310 to move to its prescribed position.

Accordingly, the stability of operation of the size detection mechanism including lateral direction width size detection member 310 provided in paper feed cassette 100 can be ensured. Moreover, erroneous detection of the paper size to be used can be avoided to maintain the reliability of operation of the image forming apparatus.

The aforementioned relation also applies between engagement shaft P5 provided at the lower end of one of side limitation plates 101 a and guide groove G1. As a result, in a manner similar to lateral direction width size detection member 310, the occurrence of clattering of side limitation plates 101 a can be suppressed, thus allowing side limitation plates 101 a to move to their prescribed positions.

Accordingly, side limitation plates 101 a can be placed in the correct positions, thereby ensuring the stability of operation of the size detection mechanism including side limitation plates 101 a. In addition, the straightness of paper feed can be improved to maintain the reliability of operation of the image forming apparatus.

Moreover, also from the standpoint of use by the user, since the occurrence of clattering of lateral direction width size detection member 310 and side limitation plates 101 a is suppressed, improved performance of adding paper to paper feed cassette 100 can also be expected.

While this embodiment illustrates, by way of example, the case where coil spring 400 is used as a biasing member, the biasing member is not limited to coil spring 400. The same function and effect as that of coil spring 400 can also be obtained by using other known biasing members.

While the embodiment described above employs the mechanism including at least three members, which are side limitation plates 101 a, link plate 320 and lateral direction width size detection member 310, as a link mechanism of the size detection mechanism, the configuration including these three members is not limiting.

For example, instead of coupling lateral direction width size detection member 310 directly to link plate 320, as shown in FIGS. 8 and 9, a link mechanism including at least four or more members, in which lateral direction width size detection member 310 and link plate 320 are indirectly coupled using a coupling rod 312, may be applied to the size detection mechanism. Specifically, lateral direction width size detection member 310 may be coupled to one end side of coupling rod 312 via an engagement shaft P4 a, while link plate 320 may be coupled to the other end side of coupling rod 312 via an engagement shaft P4 b.

In the embodiment described above, lateral direction width size detection member 310 and link plate 320 are disposed on the outer surface side of paper feed cassette 100, thereby preventing a portion of the size detection mechanism from being seen by the user, preventing a portion of the size detection mechanism from being touched by the user, and preventing the bottom sheet of paper from touching a portion of the size detection mechanism. If it is unnecessary to consider these points, however, a configuration in which lateral direction width size detection member 310 and link plate 320 are disposed on the inner side of paper feed cassette 100 can be employed.

Although the embodiments the present invention have been described, it should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims. 

What is claimed is:
 1. A paper feed cassette provided with a size detection mechanism that detects the size of paper contained in the paper feed cassette, the size detection mechanism including: a pair of side limitation plates that abuts opposite lateral sides of the paper from a width direction intersecting a paper feed direction of the paper; a link member that moves along the paper feed direction with movement of the side limitation plates in the width direction; a size detection member that is provided relative to the link member, that moves with movement of the link member along the paper feed direction, and that can enter a state in which the size detection member is abutting or not abutting an externally provided size detection sensor in the width direction of the paper; and a biasing member that provides the link member with a biasing force in a direction of the movement of the link member.
 2. The paper feed cassette according to claim 1, wherein a direction in which the link member is biased by the biasing member is a direction in which the limitation plates abut the paper in the width direction of the paper.
 3. The paper feed cassette according to claim 1, wherein the link member biased by the biasing member causes the pair of side limitation plates to press the paper.
 4. The paper feed cassette according to claim 1, wherein the size detection mechanism further includes a coupling rod that couples the link member to the size detection member.
 5. The paper feed cassette according to claim 1, comprising a bottom surface forming the bottom of the paper feed cassette, wherein the pair of side limitation plates is disposed on the inner surface side of the bottom surface, and the link member is disposed on the outer surface side of the bottom surface.
 6. The paper feed cassette according to claim 1, wherein the link member has a rotation fulcrum at an inner position in the width direction, the size detection member is shaft-supported at the link member at an outer position in the width direction as seen from the rotation fulcrum, and the biasing member is biasing the link member in a direction that causes the link member to pivot around the rotation fulcrum.
 7. An image forming apparatus comprising: an image forming unit; and a paper feed unit that stores a plurality of sheets of paper to be transported to the image forming unit, the paper feed unit including a paper feed cassette that accumulates and stores the paper, the paper feed cassette having a size detection mechanism that detects the size of the paper contained in the paper feed cassette, the size detection mechanism including a pair of side limitation plates that abuts opposite lateral sides of the paper from a width direction intersecting a paper feed direction of the paper, a link member that moves along the paper feed direction with movement of the side limitation plates in the width direction, a size detection member that is provided relative to the link member, that moves with movement of the link member along the paper feed direction, and that can enter a state in which the size detection member is abutting or not abutting an externally provided size detection sensor in the width direction of the paper, and a biasing member that provides the link member with a biasing force in a direction of the movement of the link member. 